Owing to manufacturing-dependent dimensional spread and defects of form of the outer machine part, in particular of the running disk, a difference of up to 80 μm arises between the minimum and maximum overlap in the case of an internal diameter of the running disk of roughly 55 mm.
This results in considerable differences in the transmission capacity of the compression connection between the running disk and the raceway ring of the rolling bearing if, as is known, the deformation of the running disk lies in the elastic material range (the ratio between minimum and maximum pressing force is roughly 1:3). Especially in the case of minimum overlap, there is a risk of the running disk moving away from the raceway ring of the rolling bearing. This can lead to the total destruction of a motor vehicle engine if, for example, the tensioning roller is installed in the toothed-belt drive for driving a camshaft, or the like.
Moreover, different contractions of the raceway ring occur, so that, in order to meet the demands on the rolling bearing, allocation of the rolling elements after the running disk has been pressed onto the raceway ring is necessary. This of course leads to considerable costs.
Furthermore, an uneven deformation of the raceway of the raceway ring may appear as a result of the non-roundness of the running disk, which can lead to the rolling bearing generating noise.
It is known to carry out friction-increasing coating of the contact surface of one of the machine parts. Various coatings are known from patent publications DE 195 25 965 A1, DE 197 03 821 A1, DE 197 18 307 A1 and DD 0 152 972 C.
It is true that such coatings improve the transmission capacity of the compression connection. But, they lead to additional costs and additional expenditure of labor. Moreover, they do not solve the problem of different contraction and uneven deformation of the raceway ring.